KR100639019B1 - Methods for reducing channel acquisition times in a radiotelephone communications system and related mobile terminals - Google Patents

Abstract

A communication recognition method using a communication system having a plurality of communication channels includes storing a pre-recognized communication channel in a user terminal memory. The user terminal examines the pre-recognized communication channel in the user terminal memory and recognizes the pre-recognized communication channel if a pre-recognized communication channel is available. Therefore, the number of communication recognition can be reduced.

Radiotelephone communications systems, user terminals, communication channels, CDMA, AMPS, processors, transceivers.

Description

TECHNICAL FIELD AND RELATED MOBILE TERMINAL METHODS FOR REDUCING CHANNEL ACQUISITION TIMES IN A RADIOTELEPHONE COMMUNICATIONS SYSTEM AND RELATED MOBILE TERMINALS

TECHNICAL FIELD The present invention relates to the field of communications, and more particularly to wireless telephone communications.

Cellular communication systems are commonly used to provide voice and data communication to a plurality of mobile units or subscribers. Worldwide, analog cellular systems such as AMPS, ETACS, NMT-450, and NMT-900 have been successfully deployed. In addition, digital cellular systems such as the IS-136 in North America and the GSM system in Pan-Europe have been introduced. Such and other systems are described, for example, in a book entitled " Cellular Radio Systems, " published by Balston et al., 1993, published by MA., Norwood, Artech House.

As shown in FIG. 1, the prior art cellular communication system 20 includes one or more mobile stations or units 21, one or more base stations 23, and a mobile telephone switching office (MTSO) 25. ). Although only three cells 36 are shown in FIG. 1, a typical cellular network may include hundreds of base stations, thousands of mobile stations, and one or more MTSOs. Each cell is assigned one or more dedicated control channels and one or more voice channels. For example, a typical cell may have one control channel and a voice / data or traffic channel. The control channel is a dedicated channel used to transmit cell identification and paging information. Traffic channels carry voice and data information.

MTSO 25 is the central coordinating element of the entire cellular network 20. Universally, the MTSO includes a cellular processor 28 and a cellular switch 29 and provides an interface to a public switched telephone network (PSTN) 30. Through the cellular network 20, a duplex radio communication link 32 can be obtained between two mobile stations 21 or between the mobile station 21 and a landline telephone user 33. The function of the base station 23 is generally to handle wireless communication with the mobile station 21. In this function, the base station 23 mainly functions as a relay station for data and voice signals. The base station 23 also manages the quality of the link 32 and monitors the signal strength received from the mobile station 21.

Frequency Division Multiple Access (FDMA) is commonly used in cellular technology in which several frequency groups are assigned for use in a cell that defines a limited geographic coverage area. Since cells containing the same frequency group are geographically separated, mobile units in different cells can use the same frequency simultaneously without interfering with each other. By doing so, thousands of subscribers can be served by a system with only a few hundred frequencies.

In the United States, for example, the federal authorities have allocated to cellular communications UHF frequency spectrum blocks, which are further subdivided into narrow frequency band pairs called channels. Channel pairing is represented by a frequency duplex device in which the transmit and receive frequencies of each pair are offset by 45 MHz. Currently, cellular mobile communications in the United States are assigned 832, 30-KHz wide wireless channels.

To address the capacity limitations of the analog system, a digital transmission standard called IS-136 has been provided in which the frequency channel is further subdivided into time slots. Dividing a frequency into a plurality of time slots (where a channel is formed by frequency and time slots) is called Time Division Multiple Access (TDMA). Thus, multiple channels can be formed at one frequency.

More recently, Code Division Multiple Access (CDMA) standards have been developed, where communication channels are formed by carrier frequency and pseudinoise (PN) sequences. Thus, multiple communication channels can be provided simultaneously on a common carrier frequency, with each channel on a carrier frequency having a different PN sequence. For example, the CDMA standard of cellular radiotelephone systems is provided by the Digital Cellular (IS-95) standard of North American Code Division Multiple Access (CDMA).

In any of the cellular radiotelephone systems and / or standards described above, a user terminal, such as a radiotelephone, first needs to recognize a channel before the communication service is provided by the cellular radiotelephone system. Channel recognition requires the user terminal to scan a plurality of channels to find available channels. The scan may result in a delay before the communication service is provided. This delay may be particularly important in CDMA radiotelephone systems where a channel scan is needed that first scans the available carrier frequencies and then scans the available PN sequences within the carrier frequencies.

For example, in the IS95 CDMA radiotelephone system, at the carrier frequency, each channel is encoded using a PN sequence having 32768 bits in length. Each base station in the system can use the same carrier frequency and the same PN sequence shifted by an integer multiple of 64 bits, which shift is known as the PN sequence offset. The combination of carrier frequency, PN sequence, and PN sequence offset is to specifically identify the base station / cell being monitored.

If the CDMA channel is to be recognized, the user terminal may first scan the specified carrier frequency list in the order specified in Section 6.1.1.1 of the IS-95 specification shown in Table 1 below.

Rating treason Qualified CDMA Channel List 0 A side 283,691 0 B side 384,777 One A 25,50,75,100,125,150,175,200,225,250,275 One D 325,350,375 One B 425,450,475,500,525,550,575,600,625,650,675 One E 725,750,775 One F 825,850,875 One C 925,950,975,1000,1025,1050,1075,1100,1125,1150,1175

Upon finding a carrier frequency, the user terminal examines one of 512 possible PN sequences on that carrier frequency. If no legitimate PN sequence is found on the carrier frequency, the user terminal then scans to find the next carrier frequency on which the investigation for the PN sequence is performed. The process can continue through the full spectrum of carrier frequency and PN sequence until an available channel is found. Therefore, obtaining a channel in a CDMA system may consume excessive time since it is necessary to examine the PN space for each carrier frequency in synchronization with a new carrier frequency.
U.S. Patent No. 5,640,675 entitled "Method And System For Reducing The Time For Connecting A Mobile To A Cellular Base Station" to Pinault et al., Measures the first reception level for each control frequency defined in the network. A mobile station is discussed which evaluates the movement of a mobile station by comparing the first reception level with a second reception level for each control frequency of the second list. International application WO 98/10617, entitled "Methods And Apparatus For Performing Automatic Mode Selection In A Multimode Mobile Terminal," describes control and status messages for automatically switching terminal status in both directions between a primary system and a secondary system. A wireless user terminal that includes a multi-mode controller capable of exchanging the signals in both directions is discussed.

Accordingly, there is a continuing need in the art for improved methods for communication channel survey and recognition.

It is therefore an object of the present invention to provide an improved method of wireless telephone communication and a terminal.

Another object of the present invention is to provide an improved method of scanning the available channels and associated terminals.

It is yet another object of the present invention to provide a method of reducing the time to scan available channels and associated terminals.

The above and other objects according to the present invention are directed to storing a previously recognized communication channel in a user terminal memory and examining the previously recognized communication channel in the user terminal memory, if the previously recognized communication channel is available. By recognizing a pre-recognized communication channel. Often, radiotelephone terminals have a relatively high frequency of use within a relatively small number of service areas (cells), so that communication channels associated with the most frequently used cells may have the highest availability.

In other words, the user terminal first reduces the time required to recognize the channel during a significant number of communications by examining the most likely channel before performing a thorough investigation of all expected channels. If a previously recognized channel is not available, the user terminal may add a slight delay to examine the defined channel list. In addition, the user terminal may store a plurality of previously recognized communication channels in a memory such that the investigating step includes investigating the previously recognized communication channels.

In addition, the user terminal may store an access count for each of the previously recognized communication channels, where the access count identifies the number of times each communication channel is recognized by the user terminal. Thus, the examining step may include sequentially examining the pre-recognized communication channels in the order of highest access coefficient. That is, the channel with the highest access coefficient is considered the most likely to be recognized, so the channel is examined first.

Optionally, the user terminal may check the last recognized channel among the previously recognized communication channels, and then first examine the last recognized communication channel. In this case, the last recognized channel is considered to be the channel most likely to be recognized. Also, the last recognized channel can be examined first by channel survey according to the order of the access coefficients as described above. In addition, the pre-recognized channel may be classified by a geographic search dientifier so that a pre-recognized communication channel with a common geographic search identifier may be investigated.

The method and terminal of the present invention can be advantageously used in a CDMA communication system where exhaustive investigation of the CDMA channel using carrier frequency and PN sequences can be a waste of time. Thus, each of the pre-recognized communication channels may be a CDMA channel, so that the user terminal stores a carrier frequency and a PN sequence for each of the pre-recognized communication channels. The user terminal may also store base station identification and base station location for each of the pre-recognized communication channels. Thus, the user terminal may have a pre-recognized multiple channel list having the same carrier frequency and PN sequence but different base station locations. That is, the user terminal can distinguish different CDMA channels having the same carrier frequency and PN sequence by using the location of the transmitting base station.

The method is also applicable to dual use terminals suitable for communication using both CDMA and non-CDMA communication systems. In particular, the user terminal examines the non-CDMA communication channel if the CDMA communication channel is not available. The terminal preferably provides CDMA communication if a CDMA channel is available, and provides non-CDMA communication if a CDMA channel is not available. In addition, the dual-use terminal may periodically check whether there is a CDMA communication channel available when providing non-CDMA communication, so that CDMA communication may be provided when the CDMA channel becomes available.

In the method and the terminal of the present invention, the number of irradiation can be reduced as the highest available CDMA channel is examined first. In particular, the survey may be prioritized using the most recently recognized channel, the most frequently recognized channel and / or the previously recognized channel position.

1 is a schematic diagram of a cellular radiotelephone communication system according to the prior art;

2 is a block diagram of a user terminal according to the present invention;

3 to 7 are flowcharts showing the operation of the user terminal according to the present invention.

The invention is now described in more detail with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. However, the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, the embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

A block diagram for a user terminal according to the present invention is shown in FIG. As shown, the user terminal includes a transceiver 41 for transmitting communications to and receiving communications from the radiotelephone communications system. A processor 43 is coupled to the transceiver 41 so that the processor can process communications sent and received by the transceiver. A user interface 45 is coupled to the processor 43, the user interface comprising: a keypad 45A; A visual display 45B including a liquid crystal display (LCD) and / or a light emitting diode (LED); Microphone 45C and; And a speaker 45D. The user terminal may be a wireless telephone, a portable computer, a personal digital assistant, or an electronic device other than the above suitable for wireless telephone communication. Thus, the user terminal can provide radiotelephone communication using a radiotelephone communication system as is known to those skilled in the art.

The user terminal also includes a memory 47 coupled with the processor 43, which in the present invention is used to store a pre-recognized communication channel. In more detail, data associated with each communication channel recognized in advance may be stored in the user terminal memory 47. Here, the data may include a plurality of fields as shown in Table 2 below.

field Explanation Carrier frequency Number of channels of CDMA carrier frequency that can vary for a given base station / cell PN sequence PN code (0-511) of the channel that can vary for a given base station / cell SID System Identification Number The system ID of the base station that should not change from base station / cell to firing NID network identification number Network ID of the base station that should not change for every base station / cell Longitude / Latitude Coordinates of base stations that should not change for every base station / cell Neighbor list List of PN offsets of neighboring channels that can be changed and have variable lengths Access factor The number of base stations / cells accessed Last recognized channel flag True if the terminal is the last base station / cell on; false boolean value if the terminal is not the last base station / cell on Geographic survey field A field that connects the base station / cell with one of a limited geographic survey identifier defined by a user. Data / time Last date and time the base station was accessed

As shown, the carrier frequency and PN sequence for the recognized CDMA channel can be stored. The user terminal memory may also be used to store a system identification number (SID), a network identification number (NID), a portrait / horizontal, and a neighbor list for the base station / cell transmitting the recognized CDMA channel. In addition, the user terminal memory may include: an access coefficient indicating the number of times the CDMA channel is recognized by the terminal from the transmitting base station / cell; A flag indicating whether the CDMA channel transmitted by the base station / cell is the last channel recognized by the terminal; A geographic survey field indicating an area where a base station is located in a channel; The CDMA channel sent by the base station can be used to store the last recognized date.

For a given base station, the width / length, system identification number, and network identification number should not be changed frequently, and the field is unique for identifying one of the base stations as well as a plurality of distinguished cells that are served by the base station. Can be used. However, the carrier frequency and the PN sequence of the CDMA channel transmitted by the base station may vary depending on the channel assignment for communication system changes, for example to meet changes in system usage and / or addition of base stations and cells to the communication system, and the like. have. In addition, geographically separated base stations may transmit channels having the same carrier frequency and PN sequence. Thus, although the user terminal memory may include multiple lists with the same carrier frequency and PN sequence, each of the lists should reflect that the channel was transmitted by a different base station. In addition, the base station may provide a service to only one cell, or may provide a service to a plurality of divided cells.

By using the information in the user terminal memory, the processor can first examine the CDMA channel that is most likely to be recognized according to past user terminal usage. In particular, the processor may comprise: a CDMA channel transmitted by a base station within a given geographic area as indicated by a geographic survey field; A CDMA channel transmitted by a base station with the highest access coefficient, and / or; The last recognized CDMA channel as indicated by the flag of the last recognized channel can be examined first. In addition, any CDMA channel transmitted by a base station that has not been recognized for a predetermined time period may be deleted from memory, thereby freeing memory space for a new channel.

If a pre-recognized CDMA channel from the user terminal memory cannot be recognized, the processor thoroughly examines the defined CDMA channel according to the prior art. Alternatively, the available communication channels may be examined by interleaving the specified communication channel (eg, the channels listed in Table 1) with the desired communication channel (eg, a pre-recognized communication channel). In addition, if the user terminal is a dual-use terminal that provides communication using both CDMA and non-CDMA communication systems, the processor may attempt to recognize the non-CDMA channel if the CDMA channel cannot be recognized within a reasonable time period. . In addition, an interleaved scan may be performed, in which case a predetermined length of time period is used alternately for investigation of CDMA and non-CDMA channels.

As will be appreciated by those skilled in the art, the inventive aspects of FIG. 2 described above may be provided in hardware, software, or a combination of hardware and software. In the figure, various components of the device of the present invention, such as processors, memory, transceivers, and user interfaces, are shown separated into discrete elements, but in reality, microcontrollers comprising input / output ports and operating software codes. It can be implemented integrated or separated by a custom or hybrid chip, separate components, or a combination thereof. In particular, the memory 47 and the processor 43 may be embodied as segments of additional code executed on the current memory and the current processor of the user terminal, respectively. In addition, the means used to examine the CDMA channel may be referred to as the processor. Optionally, the survey means may be said to include a processor, transceiver, memory and / or user interface functionality.

The operation of the user terminal according to the present invention is shown in the flowcharts of FIGS. 3 to 7. In particular, the flowchart of FIG. 3 illustrates an operation for recognizing a CDMA channel according to the present invention. When the user terminal is turned on, the terminal attempts to recognize a pre-recognized CDMA channel using information from the user terminal memory. In block 101, if a geographic survey option is set, the processor sorts the stored channels according to the geographic survey field so that the pre-recognized channel transmitted by the base station within the predetermined geographic area is first examined ( Block 103). At block 105, if a CDMA channel is found, the access coefficient for the CDMA channel is increased (block 117) and the channel is recognized (block 119). If this is not the case, investigation of the CDMA channel may continue.

For example, if the user moves the user terminal to an area where the terminal was previously used, the geographic survey options may be set manually by the user. Optionally, the user terminal may automatically set a geographic survey option, for example, to survey a pre-recognized channel in the geographic area where the user terminal was most recently used. The investigation of the pre-recognized channels of the predetermined geographic area may be performed sequentially in the order of the access coefficient values and / or the order of the most recently recognized channels. If no channel is recognized at all while examining a pre-recognized channel within a predetermined geographic area, then the survey continues to block 109, as shown in FIGS. 3A-3B. Optionally, if no geographic survey option is set at block 101, the survey may proceed directly to block 109. In addition, geographic information about the recognized channel may be used to classify telephone numbers in the user terminal directory invoked using the channel. Thus, the telephone directory can be sorted alphabetically and / or geographically.

In block 109, the processor attempts to recognize the channel by identifying the last channel recognized using the flag of the last recognized channel from the user terminal memory (block 111). If a channel is found at block 113, the processor increments the access coefficient for the channel (block 117) and recognizes the channel (block 119). If the last recognized channel is not found in block 113, the processor determines whether the carrier frequency for the last recognized channel can be found (block 121). If the carrier frequency can be found, the processor examines the neighbor channel list corresponding to the last recognized channel (block 123). The neighbor list provides the PN sequence of the channel for the base station adjacent to the base station of the last recognized channel. If a channel is found from the neighbor list (block 125), the channel is recognized (block 127).

If no carrier is found at block 121, or if no channel is found at block 125, the channels previously recognized from the user terminal memory are classified by the access coefficient (block 129). Next, the processor selects the pre-recognized channel with the highest access coefficient (block 131) and examines the selected channel (block 133). In block 135, if the selected channel is found, the processor increments the access coefficient for the selected channel (block 117) and recognizes the selected channel (block 119).

In block 135, if the selected channel is not found, the processor attempts to find the carrier frequency for the selected channel (block 137). If a carrier frequency is found, the processor examines the channel identified by the neighbor list of the selected channel (block 139). At block 141, if one of the channels identified by the neighbor list is found, the channel is recognized (block 119). In block 137, if no carrier of the selected channel is found, or in block 141, if the channel identified by the neighbor list is not found, the processor determines whether all of the pre-recognized channels have been examined (block 143). If none of the previously recognized channels have been examined, the processor selects the next recognized channel with the next highest access coefficient and repeats the survey (block 133).

If all of the pre-recognized channels have been investigated without finding a channel, the processor may proceed with a thorough investigation of all possible CDMA channels (block 147). The processor starts with the prescribed channel setup provided in FIG. 1 above and then proceeds sequentially through all remaining possible channels. Optionally, the processor may proceed sequentially across all remaining possible channels. In a dual-use terminal, if a CDMA channel cannot be found or if a predetermined time period has elapsed without a CDMA channel found, the terminal can proceed to a non-CDMA operation such as an AMPS operation. In addition, interleaved scan may be performed, in which case a predetermined length of time period is used alternately for CDMA and non-CDMA channel surveys, respectively. The dual use user terminal is described in more detail with respect to FIGS. 6 and 7.

If the CDMA channel is recognized as described above with respect to blocks 107, 119, and 127, the recognized channel entry is added to the user terminal memory, or the current entry of the recognized channel is described below with respect to FIG. 4. It must be updated as it is. Thus, if the CDMA channel is recognized by the user terminal (block 401), the processor examines the user terminal memory of the pre-recognized channel transmitted by the base station having the same location as the base station transmitting the recognized channel (block 405). As will be appreciated by those skilled in the art, the length and width of a base station can be transmitted by the base station in an IS-95 CDMA system, whereby the base station location can be determined by the receiving user terminal. The base station position of the recognized channel should be checked against the base station position of the pre-recognized channel, since it may need to be updated as the carrier frequency and PN sequence for the base station of the pre-recognized channel changes. .

If the base station location of the recognized CDMA channel matches the base station location of the pre-recognized CDMA channel, the processor compares the system identification number and network identification number of the recognized channel to that of the pre-recognized channel with the corresponding base station location. Check (block 409). The system identification number and the network identification number may be used to identify one of the plurality of distinct cells when one base station is used to define a plurality of distinct cells. In block 409, if the base station location, system identification number, and network identification number of the recognized channel match the pre-recognized channel, the cell where the user terminal is located is the carrier currently recognized from the pre-recognized carrier frequency and the PN sequence. You can change services with frequency and PN sequences.

Thus, no new entry is required in the user terminal entry. Instead, the carrier frequency, PN sequence, and neighbor list should be updated in the memory entry using the corresponding base station location, system identification number, and network identification number (block 411). In addition, the access factor for the entry should be increased (block 413) to reflect that the user terminal has previously been serviced in the cell, and the last used flag should be set for the channel (block 415).

At block 405, the base station location for the recognized CDMA channel does not match the base station location of any pre-recognized CDMA channel, or at block 409, the system identification number and the network identification number are any pre-recognized CDMA channel. If not, the user terminal is aware of the channel of the new cell. Thus, as indicated by blocks 417, 419, and 421, a new entry must be created for the channel in the user terminal. In particular, the access factor for the new entry is set to 1 (block 417); Carrier frequency, PN sequence, system identification number, network identification number, location (vertical / horizontal), neighbor list, and data accessed by the system are entered (block 419); The last used flag is set in the new entry (block 421).

As described above, an entry is added to the memory when the channel for the new cell is recognized. Conversely, if the pre-recognized channel is not recognized within a predetermined time as shown in FIG. 5, the entry of the pre-recognized channel in the user terminal memory may be ageed out (deleted). In particular, the processor may periodically check memory (eg, when the terminal is turned on) for memory for a previously recognized channel that is not recognized within a predetermined time (eg, six months) (block 501). The period may be set by the user. If any channel is found (block 503), then the entry for the previously recognized channel can be deleted (block 505). If no channel is found in block 503, the channel is not deleted at all.

By reducing the number of pre-recognized channels, memory space can be used for newly recognized channels. In addition, by erasing the longest recognized channel, such a channel that is not currently used is deleted. In other words, the processor considers that a channel not recently recognized is unlikely to be recognized in the future. In addition, if the memory space is almost filled, the memory may be old. In this regard, the processor can destroy the oldest known number of channels to make room for the newly recognized channel. Therefore, the user terminal may adjust the channel survey according to the change of the usage pattern.

According to another aspect of the present invention, the CDMA channel recognition operation of the present invention may be used for a user terminal adapted to communicate using both CDMA and non-CDMA (eg, AMPS) communication systems. Thus, the user terminal first obtains a performance advantage for the CDMA system by attempting to obtain a communication service from the CDMA system, and then obtains the communication service from a non-CDMA system such as an AMPS system if the CDMA system is not available. Now you can try. This operational hierarchical arrangement stipulates that CDMA communication is obtained when it is available and that non-CDMA communication is obtained as a back up to it. In addition, interleaved scan may be performed, in which case a predetermined length of time period is used alternately for investigation of the CDMA and non-CDMA channels, respectively.

Referring to FIG. 6, as described in more detail with respect to FIG. 2, the user terminal attempts to establish a CDMA communication (block 601). At block 603, if a CDMA channel is recognized, the user terminal provides CDMA communication using the CDMA communication system (block 605). As long as the CDMA communication is not lost, the user terminal processor periodically performs a rescan on the CDMA channel (blocks 609 and 611) to ensure that communication is maintained in the most available channel. If the CDMA channel is not recognized at block 603 or if the CDMA communication is lost at block 607, the user terminal attempts to recognize a non-CDMA channel such as an AMPS channel (block 613). If an AMPS channel is recognized at block 615, AMPS communication is provided (block 617). If the AMPS communication is lost at block 629, the user terminal can again try CDMA channel recognition (block 601).

During AMPS communication, the processor determines whether it is a periodic rescan time (block 619), and if so, the processor determines whether an AMPS rescan should be performed or a partial investigation of the CDMA channel should be performed (block 621). In particular, a user terminal operating in an AMPS system periodically rescans the AMPS channel so that the most available AMPS channel is available. According to the present invention, a partial CDMA channel survey may be interleaved with a conventional AMPS rescan to provide CDMA communication if a CDMA channel is available. Thus, the processor periodically starts scanning (block 619), so that a predetermined number of all scans perform partial CDMA channel lookup (block 623). The remaining scan period is used to perform AMPS rescan (block 625).

If the CDMA channel is recognized (block 627) in response to the partial CDMA channel survey (block 613), then CDMA communication is provided (block 605). Optionally, if the CDMA channel is not recognized, the AMPS operation continues (block 617). According to the present invention, CDMA communication may be provided when the CDMA channel is periodically examined during non-CDMA operation so that the CDMA channel becomes available. By interleaving partial CDMA irradiation between normally occurring AMPS rescans, the impact of AMPS operation can be reduced. Referring now to FIG. 7, the partial CDMA investigation of block 623 is described in more detail.

Since the time allotted for interleaving the CDMA channel may be insufficient to examine all the CDMA channels, it is desirable to adjust the interleaved CDMA scan so that different CDMA channels are examined during successive scans. For example, the AMPS rescan period may range from 42.6 ms to 83.2 ms. Also, prior to providing AMPS communication, in blocks 601 and 603 of FIG. 6, it was assumed that the investigation for the pre-recognized CDMA channel was not successful, and thus was not pre-recognized by the user terminal during some of the interleaved CDMA investigation. It may be desirable to examine the CDMA channel.

Thus, if an interleaved CDMA probe is selected in block 701 of FIG. 7, the processor will perform a partial probe for a pre-recognized CDMA channel, or a partial for a defined CDMA channel as shown in Table 1. Determine whether to conduct an investigation (block 703). Partial CDMA investigation may alternate between the two. Optionally, the pre-recognized CDMA channel list is partially examined once during a predetermined number of all CDMA surveys, and the remaining CDMA surveys may be used to examine the defined CDMA channel list.

At block 703, if a pre-recognized CDMA channel list is selected for the partial survey, the next channel in the list is selected (block 705), and the processor examines the selected channel (block 707). If this is the first partial survey of a pre-recognized CDMA channel list after recognizing AMPS communication, the first selected CDMA channel may be the first channel on the list. If such a partial survey was made after a previous partial survey of the inventory, the selected first selected CDMA channel may be the CDMA channel following the last examined CDMA channel in the previous inventory survey. If the selected channel is found (block 709), the user terminal provides CDMA communication (block 711).

If the selected channel is not found, the processor checks whether there is time left to examine during the rescan cycle (block 715), and if time remains, selects the next CDMA channel from the list of pre- recognized CDMA channels (block 717). ). The processor examines the selected next CDMA channel (block 707) and the cycle continues until the CDMA channel is found or the rescan cycle time expires. If no CDMA channel is found and the rescan cycle time expires, the processor stores the last examined CDMA channel in memory and returns to AMPS communication (block 719). Thus, the processor can start the next partial survey of the pre-recognized CDMA channel where the last partial survey was stopped.

Optionally, if the processor chooses to partially examine the defined CDMA channel list during the rescan period, at block 703, the processor selects the next channel from the defined CDMA channel list (block 721), thereby selecting the selected channel. Check (block 723). At block 725, if the selected channel is found, the processor provides CDMA communication (block 727). As described above, if this is the first partial search for a defined CDMA channel list after providing AMPS operation, the processor selects a first channel from the list. If such a survey was made after a previous partial survey of the CDMA channel since providing the AMPS operation, the processor selects the next channel in the list following the last channel examined in the previous survey.

If the selected channel is not found, the processor determines, at block 729, whether time remains in the rescan period. If time remains, the processor selects the next CDMA channel from the list (block 731) and examines the channel (block 723). Partial investigation of the defined CDMA channel list continues until a CDMA channel is found or until the rescan cycle time expires. If the CDMA channel is not found and timed out, the processor saves the last selected channel of the prescribed list and returns to AMPS operation (block 719). Thus, the next partial investigation of the prescribed inventory may begin where the previous investigation was discontinued.

As described above, part of the AMPS rescan period may be used to examine the CDMA channel during AMPS operation in a dual use terminal. Thus, if a CDMA channel can be used during an AMPS operation, CDMA communication can be provided. Since the defined CDMA channel list tends to be longer than the pre-recognized CDMA channel list, it is desirable that the partial search for the defined list be performed more often than the search for the pre-recognized channel list is performed.

The invention has been described above in connection with FIGS. 3 to 7 with reference to a flow chart illustrating the operation of the invention. It should be noted that each block of the flowchart and the combination of the flowchart blocks can be implemented using computer program instructions. The program instructions may be provided to a processor to generate machine language such that the instructions executed on the processor generate means for performing the functions specified in the flowchart block (s). The computer program instructions are executed by a processor such that a series of operational steps that can be executed by the processor provide for a computer-implemented process to cause the instructions executed on the processor to perform the functions defined in the flowchart block (s). Can be generated.

Thus, the flowchart block supports the combination of means for performing a specified function, the combination of steps for performing a specified function, and the program instruction means for performing the specified function. In addition, it is to be understood that each block of the flowchart and the combination of the flowchart blocks can be implemented by any intended hardware system that performs a defined function or step, or a combination of any purpose hardware and computer instructions.

In the drawings and specification, exemplary preferred embodiments of the invention are disclosed. The scope of the invention is set forth in the following claims. Although the present invention has been described above in connection with a satellite radiotelephone communication system, the method, system, and terminal of the present invention may also be applied to terrestrial cellular radiotelephone communication systems. In addition, the method, system, and terminal of the present invention can also be used using a dual mode terminal capable of providing communication using both a satellite radiotelephone communication system and a terrestrial radiotelephone communication system.

Claims (50)

In the wireless telephone communication system having a plurality of communication channels and the wireless telephone communication providing method for providing wireless telephone communication between the user terminal, Storing a plurality of pre-recognized communication channels in the user terminal memory 47, Examining available channels among the plurality of pre-recognized communication channels stored in the user terminal memory 47, If one of the pre-recognized communication channels is available, recognizing one of the pre-recognized communication channels, and And if the pre-recognized communication channel is available, providing wireless telephone communication between a user terminal and a wireless telephone communication system over the available pre-recognized communication channel. The method of claim 1, wherein the storing comprises storing an access coefficient for each of the pre-recognized communication channels, wherein the access coefficient is a number of times each communication channel has been recognized by the user terminal. Wherein the investigating step includes sequentially examining the pre-recognized communication channels in order of highest access coefficient. The method of claim 1, wherein the storing comprises identifying a last recognized channel of the pre-recognized communication channel, and wherein the investigating comprises first examining the last recognized communication channel. Wireless telephone communication providing method characterized in that. The method of claim 1, wherein the storing comprises storing a geographic survey identifier for each of the pre-recognized communication channels, wherein the investigating comprises pre-recognized with a common geographical survey identifier. And investigating a communication channel. 10. The method of claim 1, wherein each of the plurality of pre-recognized communication channels comprises a code division multiple access (CDMA) communication channel, and wherein the storing comprises: determining a carrier frequency and a PN sequence for each of the pre-recognized communication channels. And storing the wireless telephone communication. 6. The method of claim 5, wherein the storing further comprises storing a base station identification number and a base station location for each of the pre-recognized communication channels. The method of claim 6, Obtaining a base station location for the recognized communication channel, Comparing the base station location for the recognized communication channel with the base station location for the pre- recognized communication channel, Identifying a pre-identified communication channel having a base station location corresponding to the base station of the recognized communication channel, and Updating a carrier frequency and a PN sequence for the pre-recognized communication channel having the corresponding base station location. The method of claim 5, If the pre-recognized CDMA communication channel is not available, examining the available pre-recognized CDMA communication channel, If the CDMA communication channel is not available, examining a non-CDMA communication channel, and If one of the investigated non-CDMA communication channels is available, further comprising recognizing a non-CDMA communication channel. The method of claim 8, Providing communication over the recognized non-CDMA communication channel, and And periodically examining the available CDMA communication channel. 10. The method of claim 9, wherein the periodically inspecting comprises examining the pre-recognized CDMA communication channel. 12. The method of claim 10, wherein the periodically inspecting further comprises examining a CDMA communication channel that is not previously recognized. 2. The method of claim 1, further comprising deleting one of the pre-recognized communication channels if the pre-recognized communication channel is not re-recognized within a predetermined time period. The method of claim 1, wherein the storing comprises storing a neighbor communication channel list of a cell adjacent to the pre-recognized communication channel, the method comprising: If the pre-identified communication channel is not available, further comprising examining the neighboring communication channel. 2. The method of claim 1, further comprising recognizing a new communication channel if the pre-recognized communication channel is not available. A user terminal for use in a wireless telephone communication system having a plurality of communication channels, the user terminal including a transceiver 41 for transmitting wireless telephone communication to a wireless telephone communication system and receiving wireless telephone communication from the wireless telephone system. In the user terminal, A user terminal memory 47 for storing a plurality of pre-recognized communication channels, and And survey means (43) coupled to the transceiver (41) and the user terminal memory (47), wherein the survey means examines one of the pre-recognized communication channels in the user terminal memory, And recognize one of the pre-recognized communication channels if the pre-recognized communication channel is available. 16. The user terminal memory (47) according to claim 15, wherein the user terminal memory (47) stores an access coefficient for each of the pre-recognized communication channels, the access coefficient being a number of times each communication channel has been recognized by the user terminal. And said investigating means sequentially irradiates said pre-recognized communication channel in order of highest access coefficient. 16. The user terminal according to claim 15, wherein said user terminal memory (47) identifies a last recognized one of said pre-recognized communication channels, and said irradiating means first irradiates said last recognized communication channel. . 16. The user terminal memory (47) according to claim 15, wherein the user terminal memory (47) stores a geographical survey identifier for each of the pre-recognized communication channels, and the survey means surveys a pre-recognized communication channel with a common geographical survey identifier. User terminal, characterized in that. 16. The apparatus of claim 15, wherein each of the plurality of pre-recognized communication channels comprises a code division multiple access (CDMA) communication channel, and the user terminal memory 47 has a carrier frequency and a PN for each of the pre-recognized communication channels. A user terminal for storing the sequence. 20. The user terminal according to claim 19, wherein said user terminal memory (47) also stores a base station identification number and base station location for each of said pre-recognized communication channels. The method of claim 20, The investigating means obtains a base station position for a recognized communication channel, compares the base station position of the recognized communication channel with the base station position for the pre-recognized communication channel, and locates the base station position of the recognized communication channel. Identifies a pre-recognized communication channel with a base station location that matches Wherein the user terminal memory (47) updates the carrier frequency and the PN sequence for the pre-identified communication channel with the corresponding base station location. 20. The apparatus of claim 19, wherein the means for investigating examines available CDMA communication channels that are not pre-recognized if the pre-recognized CDMA communication channel is not available, and uses a non-CDMA communication channel if the CDMA communication channel is not available. Investigate, and recognize a non-CDMA communication channel if one of the investigated non-CDMA communication channels is available. 23. The CDMA system according to claim 22, wherein the transceiver (41) provides communication via the recognized non-CDMA communication channel, and the investigating means is usable while maintaining the communication via the recognized non-CDMA communication channel. User terminal characterized in that for periodically examining the communication channel. 24. The user terminal as claimed in claim 23, wherein said irradiating means periodically irradiates said pre- recognized CDMA communication channel. 25. A user terminal as claimed in claim 24, wherein said irradiating means periodically irradiates a CDMA communication channel which is not previously recognized. 16. The user terminal memory (47) according to claim 15, wherein the user terminal memory (47) stores a neighbor communication channel list for a cell adjacent to the pre-recognized communication channel, and the investigating means is further configured if the previously identified communication channel is unavailable. And examine the neighbor communication channel. The user terminal as claimed in claim 15, wherein the survey means recognizes a new communication channel if the previously recognized communication channel is not available. 16. The user terminal of claim 15, wherein the user terminal deletes one of the pre-recognized communication channels if the previously recognized communication channel is not re-recognized within a predetermined time period. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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